Turbo oil restrictors

[porsche 930twin]

Hi all just wondering what size restrictors to install on the oil feed lines to the turbos .. do not want to go to fine and starve the turbos of oil but I do not want to over feed them either...thanks in advance getting closer to dyno time..

[Alan L]

I can't answer your Q, but you are probably going to have to post more details - esp of turbos.
Alan

[Ken911]

Chris tk has several different types depending on which turbo you are using.

[JFairman]

Nobody can answer your question without knowing what turbo's you are using. Journal bearing turbo's usually get no oil restrictor. Ball bearing turbo's should have them.

When I had a Garret GSX61 ball bearing turbo with billet compressor wheel I used an oil restritor with a metering hole around .040"
It worked fine with no oil smoke.

The ball bearing GSX61 is a Garret TO4Z with a light weight CNC machined billet compressor wheel.
TurbosDirect.Com Web Site - Home in Arizona built it and they also call it an upgraded Blowzilla turbo.

It shares no parts with a Garret GT35R so if you have two of those the oil restrictor size may be different.
Like Ken said, email Chris at Turbokraft and ask him what to use. He sells very nice turbo oil restrictor kits with stainless braided oil lines.

[Ken911]

Originally Posted by JFairman

Nobody can answer your question without knowing what turbo's you are using. Journal bearing turbo's usually get no oil restrictor. Ball bearing turbo's should have them.

When I had a Garret GSX61 ball bearing turbo with billet compressor wheel I used an oil restritor with a metering hole around .040"
It worked fine with no oil smoke.

The ball bearing GSX61 is a Garret TO4Z with a light weight CNC machined billet compressor wheel.
TurbosDirect.Com Web Site - Home in Arizona built it and they also call it an upgraded Blowzilla turbo.

It shares no parts with a Garret GT35R so if you have two of those the oil restrictor size may be different.
Like Ken said, email Chris at Turbokraft and ask him what to use. He sells very nice turbo oil restrictor kits with stainless braided oil lines.

Actually if you have a turbo with bushings instead of ball bearings and it's not porsche specific it will also need a restrictor. The thrust bearings in the non ball bearing porsche specific turbos are internally restricted. So if's been rebuilt with a generic thrust bearing or from another application you'll still need a restrictor.

[porsche 930twin]

Hi all thanks for the info... turbos are Garrett running billet wheels and ceramic bearings my turbo guy recommends using 1mm restrictors but still not convinced.. will post pics tonight

[copbait73]

Technically you should size the restriction to give you 3 bar oil pressure downstream of the restrictor at peak torque engine RPM and full operating oil temperature, usually 180 degree.
Or....use the recommended 1MM fitting.

[porsche 930twin]

Hi thanks for the replies... I have installed the 1mm oil restrictors at the end of the oil feed lines right on the turbos... is this the way to go...

[1979-930]

WOW!
Looks like a serious project.
Those air filters aren’t going to stay clean very long there.


Sent from my iPhone using Tapatalk

[Alan L]

Holy crapola. Another fire breathing monster in the making.
Alan

[smurfbus]

Wastegated turbos. Is that drip tank only gravity to sump or does it go to a pump?

[Speedy Squirrel]

The 1mm or 0.040” restrictor is pretty much the standard Garrett recommendation for ball bearing turbos when you have 40 to 45 psi oil pressure (2.75 to 3.1 bar) at the turbo.

https://www.turbobygarrett.com/turbobygarrett/oil_restrictor

It is not normal for journal bearing turbos to require external restriction. They can tolerate a pretty wide range of oil pressure. The Garrett carbon face seal is a little more sensitive when the pressure behind the compressor wheel is really low, but this is something we induced in the lab. I doubt it can happen in the real world. On the other hand, restricting journal bearing pressure at the turbo oil inlet also cuts the oil flow to the turbine side, which makes it run hotter than it already does.